Safety mechanism



Aug. 14, 1951 R. F. MANKE 2,564,257

SAFETY MECHANISM Filed Aug. 30, 1946 2 Sheets-Sheet l Aug. 14, 1951 R. F. MANKE SAFETY MECHANISM 2 Sheets-Sheet 2 Filed Aug. 50, 1946 Patented Aug. 14, 1951 :iiSTATES PATENT OFFICE SAFETY MECHANISM ;;;Raym9 r 1d FQManhe, Racine, Wis, assignor to v alk ei ia f c u ne Gemnar -ofiwisc nsin, litacine, Wis, a'corporation of-Mlisconsin -Application August 30, 1946; Serial No. 69 3;9'75

'means for vehicle li-ftsof theifour post, cable-operated type, of. the-generaL-charaeter disclosed. in

the c-pending application of :FredrC. Haunzer- 'son, serial No. 737,609,2filedMarclrfl'l, 1947.

in the operationuof ilifts .of theiabove-indicated .1 Cl m -125 7135 -tion .ofwhich -corresponds-to that disclosedin the type andofl othenvarieties; the. load is sustained uh) tbyiwire rope-er cables. 1W hi-le commercially available cable is Lot-such;- reliableand uniform character: thatzthe dangen; of: failure.,-issextremely: remote eveniin the event of. long-continued neglect or labuseeit is highly desirable-mo: guard against evemsuch a-.-rernote contingency; since, men must =usua1lytwork directly beneath/the lift, and a fail- .ure might .Qcauseiidamage to valuable property evemititidid not result rinses/ere injuryor. death atonatherworkman. '5 1l'1e-:present, invention accordingly 1 has was its 2principal -:object 5 .to provide: improved, :extremely simple, rugged, reliable and quickeactingsaiety means adapted-Jo positively preventithe load; from: dronpin ;in =eyent of ;c,ab 1e failure.

Another important obj ect-ofi-the' invention is to provide -1 such}: safety; means constituting ;stlDPlemen alzmanua mh I s; .le n ;.where th sl a may :he s fel tande ow owered b ill tfi- 7 it v. rantae'e swii pb appa BDQQ'Q L ZQQ C ifiQI 9 theresen :disc os r n its ent rety.

In thegdrawipgs: i or in ctiv Vie ofza a l een e lift provided ;v;i t1'i safety means constructed in efianc -w t the; pres nt inve tion;

(1523 are-vertical sectional e1e val. I. ar i l l ok taw t mfiu s an al ecent al y;th ou h .en pa 9 co posts and thesid rail; con ect n -the ame; these wsi ein QdELPISd'J LD rea i nli xtap s io z tat he le tlt u i ;Q n ai nst-ear, .0 0 th .meehan smebeineehown- 0 a somewh treducedscale rig. 2A.

5, ectional,elevationalyiew f apart o ith eafet mechanism, show-mettle parts in tb rpo it e iihe siim ;.i ;th en of cabl 31 s ;-ai.fitae ntarx r ss-section taken su stmti ly can: .al ne Of,IF -=-3;andlookin inih ,d r ct on t earr ws.

Befe ring now; itothe drawings; referencecharst r 2 sandal.de i ateeenerallylthecorner pests 9 ihqi fi -St u9tu e :il e..s nera1 con trucco-pending application above refer-red to. In its kbroadernaspects, however, the invention is not-restricted'to details of construction of the lift, :which may: be varied withimwide limits without zdepartingrfrom "the essential attributes of the presentiinvention. Such detailswill therefore .only be considered hereinto theextent necessary fen-a complete understanding-of the present inv-i/ention.

.The load-supporting platform I consists of a frameworkaincluding :parallellongitudinal side right-hand; and leftrhand', post; and rail assem- 'bll'ie j bein ;si.milar;.-in;most respects. this descriptien, willgbe co fin dionne side of: the structure, except for such; essential features of V IdiflBI'GIICB as; exist ,between the -right and. left: assemblies. Thevfrontwend of aeach rail is provided withaa fit- .terior of; the-post; I; and guided by such slot M; duringraisingtand lowering of the lift to prevent lateralzdisplacement of therail. A somewhatisimilar;- fitting; as l 2*-is; carried"; by :the rear-{Extremity of :each raihas 16,-: and projects throughaisimilar;slotzasi [.6 in thelrear post as..2. Therails :are .thus v:posit-ively restrained against lateral displacement, as will? be; apparent. The side railsare of hollow, box-like cross section and interiorly communicateaat. their; ends with .the interiors. of the respective-corner. posts, which are also of hollow rectangular crosssection.

v-Mounted at the-tops of the front "posts i ands-i arewinchrmeansipowereda-by an electric motor 'M mounted on; the-post; I :Thewinch means carried by; thepost igomprises a.;wind1ass;drum:l8 driven byithe; motor ."through reduction gearing. generallyfle i nated zti. ..;A;-similaradnuminot shown) mounted -.coax-ia11y with atheidrum .18 within a w th through the post i, under a sheave 26 carried by the rail end fitting l9, longitudinally through the rail 6, beneath a second guide sheave 28 mounted in the fitting l2 at the rear end of the rail, and upwardly through the post 2 to an anchorage of the shock-absorbing type, generally designated 30, at the upper end of post 2. It will be seen that the cable and pulley arrangement described forms a sling-type support for the rail 6, and it will be understood that similar lifting means (not shown) is incorporated within the posts 3, 4, and the side rail 8 so that the rails 6, 8 may be raised and lowered in parallel relation by their respective Windlass drums.

Cross tie members as 32, 34 connect the side rails near their front and rear extremities, and carry load-supporting means such as the pans 35, 3'! which may be arranged to receive the wheels of a vehicle to be lifted. The front pans 35 and their ties 32 may be movable lengthwise of the rails 6-8 to accommodate the lift to different vehicle wheel bases.

In order to prevent the rails 6, 8 and the lifting frame carried thereby from tilting about a transverse axis in event a greater proportion of the load is positioned forwardly or rearwardly of the center of gravity of the lifting frame assembly, stabilizing means is housed in each of the front posts I, 3, each such stabilizing means consisting of a vertically disposed looped chain-cable assembly constructed as illustrated in Fig. 2A and including a chain section 40 meshing with and drivable by a sprocket 42, the sprocket being coaxial with respect to the drum l8 and drivable as a unit therewith by the motor M. The rear leg of the chain 40 is coupled at its lower end to a bracket portion 44 rigidly carried by and shown as formed integrally with rail end fitting l within the post I, while the cable portion M which forms the lower continuation of the chain is also coupled to the bracket portion 44 and extends downwardly therefrom, beneath the guide sheave 45 and upwardly near the front of the post to connection with the front leg of the chain to form a closed loop. It will be seen that a complete chain loop might be employed, rather than substituting cable in the lower section of the loop in the manner disclosed, although the use of cable in the lower portion is preferred since it simplifies the lower guiding sheave means 45 and is somewhat quieter in operation. The coupling means for the rear legs of the coaxial chain-cable portions is designated 46.

Since a two-to-one speed reduction of the drive imparted to the lifting frame is effected by the single sling support arrangement, the diameter of the sprocket 42 is half that of the drum l8, and the front end of rail 6 is accordingly driven by the chain at the same rate as the average driving speed imparted to the rail by the main cable 25. Differential driving of the rail, and consequent tilting of the same about .a transverse axis due to unequal loading, is prevented, however, by the positive driving connection provided by the chain and sprocket drive. The lifting frame assembly is accordingly positively maintained in horizontal position at all times since, as previously indicated, similar stabilizing 'means is also associated with the other side rail 8 within the corresponding front post 3.

The motor M is not drivable by the load, whether or not the motor is energized. It will be recognized that such an irreversible drive may be provided in any of various ways, as by the design of the gear reducing means 20, or by the 4 provision of friction drag means acting upon the motor shaft, so that the effect of the drag upon the motor is relatively slight, but is multiplied by the gearing to render the drive irreversible. In the construction shown, such a friction drag is incorporated but not illustrated, since it forms no part of my present invention. It may be housed within the supplemental casing portion 56 mounted on the post I and supported by the winch housing portion 38 carried by the top of the post. The details of a suitable friction brake of this character are disclosed in Willard T. Walker Patent No. 1,958,026, issued May 8, 1934, although it will be appreciated that any suitable design might be employed. By reason of the irreversible character of the Windlass drive, the stabilizing means in the front posts not only function whether or not the motor is energized, but serve as safety mechanism adapted to sustain the front ends of the rails 6, 8 in event of failure of one or both of the main cables.

Automatic safety means are also provided arranged to prevent dropping of the rear ends of the rails in event of such a cable failure. It will be appreciated that each of the posts 2, 4 incorporates an independent safety device although onl the device within post 2 is illustrated. As shown in Fig. 2B, the vertically disposed screw shaft 52 is mounted within the post 2 and provided with helical threads extending the full length of the vertical travel of the lift. The screw shaft is supported at its upper end by means of a rigid bracket 54 welded or otherwise secured in place and also serving to support the anchoring means 30 for the main cable 25. The screw shaft is provided with a squared upper extremity as 56, or otherwise suitably contoured to receive a hand crank or wrench (not shown) and is provided with a shoulder shown as formed by a welded-on washer 58 overhanging the bracket 54 and preventing downward movement of the shaft but permitting the same to be rotated about its longitudinal axis. The bracket 54 may be reinforced beneath the portion thereof which supports the shaft, as by means of the relatively heavy angle bracket 60. The shaft depends through a tubular guide portion 62 carried by and shown as formed integrally with the rear end fitting l2 of the rail 6, the smooth cylindrical inner surface of tubular portion 62 being proportioned to slide freely over the surface portions of the helical thread of the shaft. It will be noted that shaft 52 is spaced from but extends parallel to the portion of the cable 25 which projects upwardly through the post 2, when the cable is in its normal operating position.

A lever-type locking dog 65 is pivoted in the fitting I2 upon a cross pin 66, located between the aforementioned vertical portion of cable 25 and the shaft 52 and rockable substantially in a plane passing through the axes of both the cable and shaft. At its lower extremity the dog is provided with teeth 68 proportioned tointerfit with those of the shaft when moved into engagement therewith by counterclockwise rotation of the dog, as viewed in Fig. 2B. The upper arm of the dog carries a roller 10 which normally engages the aforementioned vertical portion of the main cable 25, thereby holding the toothed portion 68 out of engagement with the shaft 52. In normal operation of the lift, the roller 10 moves freely up and down the cable 25 while the tubular portion 62 slides freely over the shaft 52.

The toothed portion 68 is constantly urged to-= ward the shaft 62, however, by a helical comtbre fsie sprin 2 t p na t ne opposi gand inwardly facing socketed portions :fiundes- ,-.ign a ted)- formed in the upper portion of the de and the opposed inwardly facing portion of the ,tub,ular,;section ,62,. respectively. It=will .be apprecia ted that so longasthe main cable remains in, its normal operating. condition, the dog cannot rockto a position to permit teeth 68 to engage thoseof the shaft, but that inevent of failure of the: cable its resultant slackening immediately permits counterclockwise rotation of .the .dog as .viewedjrt Fig 213,, under the influenceof spring 412.. so that the. teeth 68,.- engaging the;-teeth,;-,of atbe shaft 52 which is held by; the wallssofthe tubular portion. 62 against movement away from the Vdog,,65. ,Theshaft 52.will therebyessume and sustain the load of the rail 6,; preventing the same and the load carried thereby from dropping appreciably. v

.ilmorder, to .lower the; load after such a -ca ble .;fai lu re,it is only necessary-toapply a crank, wrench or vothersuitable: rotating. means tothe squared upper extremity, 56, and turn the screw shaft 62 in a direction to lower. the dgg fi5, the

,-,toothed portion 68; ofwhichthenserves-as a -;nut permitting the rear. end of raiL-Sand the;con-

nected,load=sustaining framework tobe manuallylowered. -I he-cover;portion 89 which is carried at the top of post 2 is removable to afford access to the crank-receiving portion 56. be appreciated alsowthatin order to lower the .iron men ion o a 6 an the-ran it. as-

suming that the cable for thezrail finhas ,not failed, thelmotorilvl maybe operated slowly or intermittently, at a rate corresponding to the sscr-ibedwwhile the -rail-8--islowered by itscable and Windlass means in the normal manner and at the same rate.

While it will be apparent that the preferred embodiment herein described is well calculated to achieve the objects and advantages first above stated, it will be apparent that the invention is susceptible to variation, modification, and change within the spirit and scope of the subjoined claims.

Having thus described the invention, I claim:

1. In combination with a lift mechanism of the cable-operated type comprising a main cable including a normally taut portion, and load-supporting means actuable by such cable, safety means for preventing unwanted falling of such load supporting means in event of cable failure, comprising an elongated supplemental holding abutment member rigidly supported in a position parallel to the normal path of movement of such load-supporting means, safety holding means including a lever pivoted to said load-supporting means and movable to and from engagement with said abutment member, said lever having a portion adjacent said normally taut portion'and engageable therewith and actuatable by said taut portion for normally maintaining said holding means out of engagement with said abutment member, and means rendered effective as a result of the slackening of the cable taut portion for moving said holding means into a position to engage said abutment member.

2. Means as set forth in claim 1 in which said abutment member is provided with a plurality of abutment portions serially arranged therealong,

It will an sai shpldine-lm an i enseeeab ;ii -ei r 'Of; such portionsin accordance with;,;the l gitudinalpositioning of the lead supporting means.

:3. Means as set forth in claim 1 in-vvhich said abutment member; comprisesea .screw shaft grotatable about its axisbut held againstunwanted .4. In :combination with a lift mechanism pf the cable-operated type comprising a main cab le ,includ-ing a normally taut portion and load-supporting means actuable by such cable, combined .safetyumeans and manual-operating mean for contrclling ;the descent of such loadrsupporting -.means ,in ,event. of l ,cable failure,v comprisinga screw;threaded. shaft mounted in a ppsitio allel, ,to the normaLpathof movem'ent -of, ,su ch load-supporting means and ,held agains't ,movevment therewith but rotatable about its longitudina1 axis, ,,a ,safety holding element gcarrieds by said load-supporting .means and movable tqarid fromengagement with the threaded .por tion.,of

.said shaft, means normally maintaining said ho din -e m out o en ae me 'wit tb shaft, and means responsive to. slackening; ,ofsthe cable; for moving said element into ,engiagement wi su hportion of the, haft.

5. Means as set forth in claim 1 in which-said abutment member comprises 7 a screw. shaft ;.ro-

tatebl abcut t ax b h l a in t n ante lon itudinal displac me t and p ov ded w th thread means of irreversible pitchisaidholdiii means being engageablevvithsaid teeth to., s er.ve

.. a lock dos an ne el a ainst rqta b with the shaft whereby the holding means may serve as a nut to enable actuation of the loadsupporting means by rotation of the shaft, the screw shaft and taut portion of the cable being arranged in spaced parallel and vertical relation and the holding means comprising a dog pivoted upon the load-supporting means having mutilated teeth movable to and from engagement with the thread means of the shaft by rocking movement of the dog, and a restraining portion engageable with the taut portion of the cable and normally preventing the teeth from engaging the shaft.

6. In combination with a lift mechanism of the cable-operated type comprising a main cable arranged to support a load-supporting means, combined safety means and manually operable means for controlling the descent of such load-support ing means in the event of a cable failure, comprising' a screw-threaded shaft mounted in a position parallel to the normal path of movement of such load-supporting means and held against longitudinal movement therewith but rotatable about its longitudinal axis, a safety holding element, means pivotall securing said element to a rigid portion of said load supporting means for movement to and from engagement with the threaded portion of said shaft, said securing means holding said element against rotation about the axis of said shaft, means normally maintaining said element out of engagement with the shaft, and means responsive to a failure of said cable for moving said element into engagement withsuch shaft portion.

'7. In combination with a lift mechanism of the cable-operated type comprising a main cable arbined safety means and manually operable means for controlling the descent of such load-supporting means in the event of a cable failure, comprising a screw-threaded shaft mounted in a position parallel to the normal path of movemerit of such load-supporting means and held against longitudinal movement therewith but rotatable about its longitudinal axis, a safety holding element, means pivotally securing said element to a rigid portion of said load supporting means for movement to and from engagement with the threaded portion of said shaft, said securing means holding said element against rotation about the axis of said shaft, means normally maintaining said element out of engagement with the shaft, and means responsive to a failure of said cable for moving said element into engagement with such shaft portion, said element being effective as a consequence of the engagement of said element with said shaft to exert a frictional force on said shaft for holding said shaft against rotation about its axis.

8. The combination of claim 6 in which said element comprises a toothed dog and in which a sleeve member fixed relative to said load-supporting means surrounds said shaft with a sliding fit, means pivotally securing said dog relative to said sleeve'member so that said shaft is held within predetermined limits of transverse deflection due to the force applied by said dog transversely of said shaft when said dog is in engagement with said shaft.

9. In an elevatable structure, an elevatable platform, a sheave carried by said platform, a supporting member positioned at an elevation above the maximum elevation to which said sheave is to be raised, a main cable having a portion secured to said supporting member and extending therefrom to said sheave, means folr pulling said cable about said sheave whereby said platform is elevated, an elongated member supported against longitudinal movement and positioned parallel to the path of movement of the axis of said sheave during movement thereof with said platform, a dog, means pivotally securing said dog to an element movable with said platform, means normally biasing said dog into a position engageable with said elongated member whereby longitudinal movement of said dog along said elongated member is prevented, and means engageable with the portion of said cable intermediate said sheave and said supporting member and acting to hold said dog in a rotated position out of engagement with said elongated member when said cable portion is taut.

10. The combination of claim 9 in which said elongated member is a rod and is manuall rotatable about its longitudinal axis and is provided with helically arranged screw threads of small pitch and in which the portion of said dog engageable with said elongated member has mating screw threads.

11. The combination of claim 10 in which said pivotally securing means holds said dog against rotation about the axis of said elongated member.

RAYMOND F. MANKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 219,367 Schmitt Sept. 9, 1879 401,106 Backman Apr. 9, 1889 1,390,111 Fettinger Sept. 6, 1921 1,990,241 Mizer Feb. 5, 1935 

